A population-based patient study will be conducted to examine the mediators of ethnic disparities in breast cancer prognosis and survival. Eligible cases of histologically confirmed female breast cancer between the ages of 21 and 79 will be ascertained through hospitals in Chicago, IL. Non-Hispanic White, non-Hispanic Black and Hispanic patients will be interviewed between 8 and 12 weeks after diagnosis and medical records will be abstracted 6 months after diagnosis. Prognostic outcomes will be defined as the pathologic stage at diagnosis, estrogen receptor status, and histologic grade. We will define four "mediating variables" hypothesized to intervene on breast cancer survival at different times. Path to Detection (through mammography screening or not), Time to Contact (from first sign or symptom to first contact with the health care system), and Time in System (from first contact to first therapeutic intervention) are hypothesized to influence survival by influencing the extent of disease at treatment. A fourth variable, Treatment Given, is hypothesized to influence survival independent of disease stage at treatment. We will establish how the first three variables influence prognosis, and whether or not ethnic differences exist with respect to all four variables. We will then seek to determine factors responsible for ethnic variation in the mediating variables. Using mixed models for binary and continuous response, we will model variation in each mediating variable as a function of individual and aggregate level socioeconomic status and health care system factors. Treatment variation will be further explored with respect to patient attitudinal variables. Patient interview data, medical record data, health care system information, and unique neighborhood survey data for Chicago will be combined to conduct a detailed and thorough examination of the mediating factors for ethnic disparities in breast cancer prognosis.